Sensing system with auxiliary display

ABSTRACT

A system is provided for sensing blood glucose data of a patient. The system includes a sensor, user interface, and an optional auxiliary device. If the connection between the sensor and user interface is by a wire, the sensor remains powered when the wire is disconnected. The communication between the sensor and the user interface may be wireless. The auxiliary device can be a patient monitor or other display or signal device, which displays information about the blood glucose data collected by the sensor. The sensor is connected to sensor electronics, which include a sensor power supply, a voltage regulator, and optionally a memory and processor.

RELATED APPLICATION DATA

This is a continuation of U.S. patent application Ser. No. 11/980,149,filed Oct. 30, 2007, now U.S. Pat. No. ______, which is a continuationof U.S. patent application Ser. No. 10/899,623, filed Jul. 27, 2004, nowU.S. Pat. No. 7,344,500, which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a sensing system including aphysiological characteristic sensor, a user interface, and an auxiliarydevice. The invention more specifically relates to a blood glucosesensor which remains powered and performs functions when disconnectedfrom communication with the user interface. The auxiliary device may bea display device.

2. Description of Related Art

Test strip meters are used to measure the blood glucose level forpatients that do not have metabolic control. Frequent measurements areneeded to intervene and control glucose levels, but frequently using atest strip meter is labor intensive. For example, in hospitals today,nurses need to take discrete blood glucose measurements from manypatients each hour. An automated frequent measurement apparatus andprocess are needed to relieve nursing labor.

Medical sensing systems designed to measure a physiologicalcharacteristic of a patient generally consist of a sensor and a userinterface for setting up the sensor and observing data from the sensor.Typically, the sensor requires power, which is supplied by the userinterface or by electronics that accompany the sensor on the user'sbody. In some environments, it is inconvenient for a person to wear thesensor and the accompanying electronics or user interface, especially ifthe electronics are large such as a wall mounted display. For example,in a hospital, it is common to have patient monitors that display dataabout patients, such as heart rate, blood pressure and the like. If asensor is in communication with a patient monitor, it may be needed ordesired to remove the sensor. Yet, the patient cannot always remove thesensor as needed or desired, especially if the sensor is difficult toremove or if the sensor is a single use device, which must be replacedwith a new sensor each time it is removed. Thus, new systems are neededthat allow the patient to wear the sensor continuously, without theconstant inconvenience of a user interface.

BRIEF SUMMARY OF THE INVENTION

In embodiments of the present invention, a sensing system is provided tomeasure a physiological characteristic of a patient. The physiologicalcharacteristic is preferably blood glucose concentration, but may alsobe, in addition or in lieu of blood glucose concentration, theconcentration of oxygen, potassium, hydrogen potential (pH), lactate,one or more minerals, analytes, chemicals, proteins, molecules,vitamins, and the like, and/or other physical characteristics such astemperature, pulse rate, respiratory rate, pressure, and the like.

The sensing system includes a sensor and a user interface. The sensingsystem may also include an auxiliary device. The sensor may be asubcutaneous sensor, vascular sensor, or non-invasive sensor. The userinterface may be a handheld device, such as a handheld computer,personal data assistant (PDA), telephone, remote control, and the like.The auxiliary device is preferably a patient monitor.

The sensor may be a blood glucose sensor, wired to a user interface,which is wired to an auxiliary device, preferably a patient monitor. Thesensor may preferably be a real-time sensor. The user interface mayprovide power to the sensor and/or the monitor may provide power to thesensor. Alternatively, the monitor may recharge the user interface,which powers the sensor. The user interface may be detached from thepatient monitor while the sensor is still powered and working. The userinterface may transmit data wirelessly to the monitor. Alternatively,the glucose sensor may be wired to both a user interface and a patientmonitor. The sensor may be powered by the user interface, monitor, orboth.

A blood glucose sensor and sensor electronics may be wired to a userinterface. The sensor and sensor electronics can detach from the userinterface. The sensor may remain powered by the sensor electronics whenthey are detached from the user interface. The sensor electronics mayalso be recharged when attached to the user interface. The sensor andsensor electronics may retain power, reference values (e.g., forcalibration), and sensor measurements when detached from a first userinterface. The sensor and sensor electronics can then be attached to asecond user interface where they will download sensor measurements to bedisplayed, and the sensor and sensor electronics will not requirerecalibration or warm up due to attaching with a second user interface.

A user interface or monitor may supply power to sensor electronics usinga transformer, thus providing ground isolation between the userinterface and the sensor electronics. The sensor electronics may includea connector for wired connection to a user interface or monitor. Theuser interface may include a wired connection for connecting to apatient monitor.

The sensor may include a connector for connecting to sensor electronics.The sensor electronics power supply may be activated when the sensor isconnected.

Further according to the present invention, a blood glucose sensor andsensor electronics may communicate with a user interface, whichcommunicates with a monitor. The communications may be wired orwireless. The blood glucose sensor and sensor electronics maycommunicate to both a user interface and a monitor.

The sensor electronics may include factory supplied reference values fora sensor. The factory supplied reference values may be stored in anonvolatile memory, which can also be placed into a user interface forcalibrating sensor signals. Reference values can be communicated to thesensor electronics or user interface directly from a blood glucosemeter. The reference values can be downloaded to a personal computer ormanually entered into a personal computer and then uploaded to the userinterface and optionally sent to the sensor electronics. The referencevalues can be manually entered into the user interface and optionallysent to the sensor electronics.

The sensor electronics may include one or more of a sensor power supply,a regulator, a signal processor, a measurement processor, a measurementmemory and a reference memory. The user interface may include one ormore of a user interface power supply, a user interface processor, areference memory, a measurement processor, a measurement memory, asignal processor, a regulator, and a mechanism for receiving data froman input device and/or sending data to an output device. The userinterface and sensor electronics may either or both include a wirelesscommunication mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of embodiments of the invention will be made withreference to the accompanying drawings, wherein like numerals designatecorresponding parts in the figures.

FIG. 1A is a communication flow diagram of a sensor and user interfacein accordance with an embodiment of the present invention.

FIG. 1B is a communication flow diagram of a sensor and user interfaceand auxiliary device in accordance with an embodiment of the presentinvention.

FIG. 1C is a communication flow diagram of a sensor and user interfaceand auxiliary devices in accordance with an embodiment of the presentinvention.

FIG. 1D is a communication flow diagram of a sensor and user interfaceand auxiliary device in accordance with an embodiment of the presentinvention.

FIG. 1E is a communication flow diagram of a sensor and user interfaceand auxiliary device in accordance with an embodiment of the presentinvention.

FIG. 1F is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 1B.

FIG. 1G is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 1B.

FIG. 1H is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 1C.

FIG. 2A is an information flow diagram of a sensor, sensor electronics,and user interface in accordance with an embodiment of the presentinvention.

FIG. 2B is an information flow diagram of a sensor, sensor electronics,user interface and display device in accordance with an embodiment ofthe present invention.

FIG. 2C is an information flow diagram of a sensor, sensor electronics,user interface, and display devices in accordance with an embodiment ofthe present invention.

FIG. 2D is an information flow diagram of a sensor, sensor electronics,user interface, and display device in accordance with an embodiment ofthe present invention.

FIG. 2E is an information flow diagram of a sensor, sensor electronics,user interface, and display device in accordance with an embodiment ofthe present invention.

FIG. 2F is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 2B.

FIG. 2G is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 2B.

FIG. 2H is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 2B.

FIG. 2I is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 2B.

FIG. 2J is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 2C.

FIG. 2K is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 2C.

FIG. 2L is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 2D.

FIG. 2M is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 2D.

FIG. 2N is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 2D.

FIG. 2O is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 2D.

FIG. 2P is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 2E.

FIG. 2Q is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 2E.

FIG. 2R is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 2E.

FIG. 2S is diagram of an embodiment of the present invention inaccordance with the information flow diagram of FIG. 2E.

FIG. 3A shows a sensor in accordance with an embodiment of the presentinvention.

FIG. 3B shows a sensor with incorporated electronics in accordance withan embodiment of the present invention.

FIG. 3C shows a sensor connected with a previously separate sensorelectronics that includes a wire for connecting to another device inaccordance with an embodiment of the present invention.

FIG. 4A shows a sensor connected to a previously separate sensorelectronics including a transmitter in accordance with an embodiment ofthe present invention.

FIG. 4B shows a sensor connected to a previously separate sensorelectronics including a transmitter in accordance with an embodiment ofthe present invention.

FIG. 4C shows a sensor and electronics encased in a housing whichincludes a transmitter in accordance with an embodiment of the presentinvention.

FIG. 5A is a block diagram of a user interface and sensor in accordancewith an embodiment of the present invention.

FIG. 5B is a block diagram of a user interface, auxiliary device andsensor in accordance with an embodiment of the present invention.

FIGS. 5C and 5D are block diagrams of a user interface, sensor andsensor electronics in accordance with embodiments of the presentinvention.

FIGS. 5E and 5F are block diagrams of a user interface, sensor andsensor electronics in accordance with embodiments of the presentinvention.

FIG. 5G is a block diagram of a user interface, sensor and sensorelectronics in accordance with an embodiment of the present invention.

FIG. 5H is a block diagram of a user interface, sensor and sensorelectronics in accordance with an embodiment of the present invention.

FIGS. 6A and 6B are block diagrams of a user interface, sensor andsensor electronics in accordance with embodiments of the presentinvention.

FIGS. 6C and 6D are block diagrams of a user interface, sensor andsensor electronics in accordance with embodiments of the presentinvention.

FIG. 6E is a block diagram of a user interface, sensor and sensorelectronics in accordance with an embodiment of the present invention.

FIG. 7 shows a sensor and sensor electronics, user interface, and flashmemory card in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, reference is made to the accompanyingdrawings, which form a part hereof and which illustrate severalembodiments of the present inventions. It is understood that otherembodiments may be utilized and structural and operational changes maybe made without departing from the scope of the present inventions.

As shown in the drawings for purposes of illustration, the invention maybe embodied in a physiological characteristic sensing system including aphysiological characteristic sensor, such as a blood glucose sensor,that generates physiological characteristic data to be sent to one ormore devices, such as a user interface and/or an auxiliary device. Thephysiological characteristic data may be displayed on the auxiliarydevice.

Physiological characteristics are generally used in a hospital to detectwhen a patient needs a therapy change and to quantify the therapeuticchange required. For example, a patient's blood glucose level may bemeasured to determine if they have lost metabolic control. If they havelost metabolic control, a caregiver can use the blood glucosemeasurement to determine changes to therapy. Hospital patients may lackmetabolic control due to trauma, stress of surgery, stroke, heartconditions, myocardial infarction, hypertension, diabetes, organtransplant, infections, sepsis, renal diseases, pregnancy, physical,mental or emotional distress, and the like.

In other embodiments, lactate sensors may be used to detect a patient'sblood lactate concentration. Lactate concentrations can be used todetect whether a patient has had a myocardial infarction or whether apatient is septic. Rising lactate levels can indicate that a patient isbecoming more septic, and lowering lactate levels can indicate that apatient is recovering from sepsis. Lactate levels may also be used todetermine how efficiently a patient's tissue is using oxygen. As thetissue oxygen exchange decreases, the lactate level increases, andcaregivers can detect that the patient is becoming more ill.

FIGS. 1A-1H show wired connections between a sensor 100 and one or moredevices according to embodiments of the present invention. The one ormore devices include at least a user interface 200 and may include oneor more auxiliary devices 300. There may be a connector between wiredcomponents (not shown). As shown in FIG. 1A, the present invention mayconsist of a sensor 100 in communication with a user interface 200. Thesensor 100 is powered by the user interface 200, and the sensor 100measures a physiological characteristic, such as blood glucoseconcentration.

The sensor may continuously measure a physiological characteristic, andthen measurement updates would be displayed periodically on one or moredevices. The sensor measurements may be real-time, and thus would bedisplayed as soon as the measurement is available. Alternatively, morethan one measurement may be collected before a measurement is displayed.The measurements also may be stored until all measurements are taken andthen displayed. The measurement may also be delayed before it isdisplayed.

The sensor may also measure, in addition or in lieu of blood glucoseconcentration, the concentration of, oxygen, potassium, hydrogenpotential (pH), lactate, one or more minerals, analytes, chemicals,proteins, molecules, vitamins, and the like, and/or other physicalcharacteristics such as temperature, pulse rate, respiratory rate,pressure, and the like. The sensor may be an electro-chemical sensorplaced through skin into the subcutaneous tissue of a body such as thesensor described in U.S. Pat. Nos. 5,390,671, 5,391,250, 5,482,473, and5,586,553, and U.S. patent application Ser. No. 10/273,767 (published asU.S. patent publication no. 2004/0074785 A1, Apr. 22, 2004), which areherein incorporated by reference. Alternatively, the sensor may be ablood contacting sensor. For example, the sensor may be a thin filmvascular sensor such as described in U.S. Pat. Nos. 5,497,772,5,660,163, 5,750,926, 5,791,344, 5,917,346, 5,999,848, 5,999,849,6,043,437, 6,081,736, 6,088,608, 6,119,028, 6,259,937, 6,472,122, and6,671,554, and U.S. patent application Ser. Nos. 10/034,627 (publishedas U.S. patent publication no. 2003/0078560 A1, Apr. 24, 2003), Ser. No.10/331,186 (published as U.S. patent publication no. 2004/0061232 A1,Apr. 1, 2004), Ser. No. 10/671,996 (published as U.S. patent publicationno. 2004/0061234 A1, Apr. 1, 2004), Ser. No. 10/335,574 (published asU.S. patent publication no. 2004/0064156 A1, Apr. 1, 2004), Ser. No.10/334,686 (published as U.S. patent publication no. 2004/0064133 A1,Apr. 1, 2004), and Ser. No. 10/365,279 (published as U.S. patentpublication no. 2003/0220552 A1, Nov. 27, 2003), which are hereinincorporated by reference. Alternatively, the sensor may be non-invasiveand thus, does not penetrate into the body such as optical sensors andthe sensor described in U.S. patent application Ser. No. 09/465,715,(published as PCT application no. US99/21703, Apr. 13, 2000), which isherein incorporated by reference. The sensor may preferably be areal-time sensor. As used herein, the terms “real-time” and “real-timesensor” refer to a sensor that senses values substantially continuouslyover an extended period of time and makes such values available for useas the values are being sensed and collected rather than having todownload substantially all the collected values at a later time for use.For example, a real-time blood glucose sensor might sense glucose valuesevery 10 seconds over an extended period of 24 hours, and make thevalues available (e.g., processing, charting and displaying) every 5minutes so that that users of an insulin pump have the flexibility tofine-tune and start or stop insulin delivery upon demand. Patients maythus use their pumps to make substantially immediate therapy adjustmentsbased upon real-time continuous glucose readings displayed every 5minutes and by viewing a graph with 24-hour glucose trends. For example,the sensor may be as described in U.S. patent application Ser. No.10/141,375 (published as U.S. patent publication no. 2002/0161288 A1,Oct. 31, 2002), hereby incorporated by reference, and the view ofdisplayed data may be as described in U.S. patent application Ser. No.10/806,114, which is herein incorporated by reference.

In preferred embodiments, sensor measurements are displayed every 5minutes. Alternatively they may be displayed more frequently such asevery 2 minutes, every minute, or every 30 seconds. In other embodimentsthe sensor value is displayed less frequently such as every 7 minutes, 8minutes, 10 minutes, 15 minutes, 20 minutes, 30 minutes, 1 hour, and thelike. Periodically a nurse may observe a patient's present blood glucoselevel and adjust the patient's therapy such as changing the insulindelivery rate (e.g., increasing or decreasing the rate that a pumpsupplies insulin to the patient's body through intravenous orsubcutaneous delivery), providing an extra bolus of insulin (e.g.,injecting extra insulin into the patient's body, or into the patient'sIV line, or by programming an insulin pump to infuse an extra dose ofinsulin), change the patient's food intake (e.g., increasing ordecreasing the rate that glucose is delivered into the patient's body,or changing the rate of tube feeding, or giving the patient food toconsume), changing the amount of drugs that the patient is using thataffect insulin activity such as medications to treat type 2 diabetes,steroids, anti-rejection drugs, antibiotics, and the like. The nursemight check the patient's glucose level and make an adjustment totherapy as needed every hour. Alternatively, a nurse may see if anadjustment is needed more frequently such as every 30 minutes, 20minutes, 10 minutes and the like. This is especially likely if thepatient's glucose level is not in a normal range. Alternatively a nursemay see if an adjustment is needed less frequently such as every 2hours, 3 hours, 4 hours, 6 hours and the like. This is more likely ifthe patient's glucose level is in the normal range; or, if the patient'sglucose has been normal for a period such as 1 hour, 2 hours, 4 hours,or 8 hours; or if the patient's therapy has not changed for a periodsuch as 2 hours, 4 hours, 8 hours or 12 hours. In further alternatives,nurses may rely on alarms to notify them to check on the patient. Forexample, nurses might rely on glucose alarms to tell them that glucoselevels are too high or too low before they see if a therapy adjustmentis needed, they might rely on an alarm to tell them that it is time tocalibrate the sensor, they might rely on a time activated alarm to tellthem that it is time to check in on a patient, they might rely on analarm to tell them that the equipment needs to be cared for, and thelike.

A normal range for a patient's blood glucose level in the hospital istypically between 80 and 120 milligrams of glucose per deciliter ofblood (mg/dl). Some caregivers maintain a higher normal range with theupper limit of the range at about 140 mg/dl, 145 mg/dl, 150 mg/dl, 160mg/dl, and the like and the lower limit of the range at about 70 mg/dl,80 mg/dl, 90 mg/dl, 100 mg/dl, 110 mg/dl, and the like. Other caregiversmaintain a lower normal range with the upper limit of the range at about110 mg/dl, 100 mg/dl, 90 mg/dl, 80 mg/dl, and the like and the lowerlimit of the range at about 80 mg/dl, 70 mg/dl, 60 mg/dl, 50 mg/dl, andthe like.

A caregiver may use the present blood glucose value to adjust apatient's therapy to bring the patient's glucose to within a normalrange. For example, if the patient's glucose level is higher than thehigher end of the normal range, the caregiver may increase the rate thatinsulin is delivered to the patient's body. Conversely, if the patient'sglucose level is below the lower end of the normal range, the caregivermay decrease the insulin delivery rate.

Alternatively, the caregiver may consider both the present and at leastone older glucose value to determine adjustments to the patient'stherapy. For example, if the present glucose level is too high and aprevious glucose level was lower, then the caregiver may substantiallyincrease the insulin rate because the patient's glucose is too high andrising.

The caregiver may use trend information or a graphical plot of glucosevalues over time to determine if the patient's therapy should bechanged. Alternatively, the therapy may be changed automatically whenthe patient's glucose level is drifting out of the normal range.

The user interface 200 allows a user to interact with the sensor. Theuser interface may include one or more of: an output device such as aliquid crystal display (LCD), a light emitting diode (LED), a touchscreen, a dot matrix display, plasma display, alarm, buzzer, speaker,sound maker, voice synthesizer, vibrator, and the like; an input devicesuch as a keypad, one or more buttons, a keyboard, a mouse, a joystick,a radio frequency (RF) receiver, an infrared (IR) receiver, an opticalreceiver, a microphone, and the like. The user interface may be ahandheld device such as a handheld computer, a personal digitalassistant (PDA), a cell phone or other wireless phone, a remote control,and the like. Alternatively, the user interface may be a personalcomputer (PC), a desk top computer, a lap top computer, and the like.

As shown in FIG. 1B, the user interface 200 may also be in communicationwith an auxiliary device 300, such as a patient monitor. A patientmonitor includes any display or other indicator system intended to beused in a hospital, doctor's office, or other medical setting, includinghome medical use. For example, some patient monitors are used in ahospital environment to monitor physiological characteristics of apatient, such as the patient monitors described in U.S. Pat. No.6,733,471, hereby incorporated by reference.

Although the arrow from the user interface 200 is shown transmittingdata to auxiliary device 300 and not in reverse, this is not in any wayintended to be limiting. In any of the figures shown, the transmissionof data may occur in either, or both, directions. The communication maybe over a wired connection or by wireless methods. Wireless methodsinclude methods such as radio frequency (RF) communication, infrared(IR) communication, optical communication or any other wireless methodthat would be useful in connection with the present invention as wouldbe readily appreciated by one of ordinary skill in the art without undueexperimentation.

As shown in FIG. 1C, the user interface 200 may communicate with one ormore auxiliary devices 300. The one or more auxiliary devices 300 maycommunicate with each other in addition to the user interface 200 and/orthe sensor 100 directly.

As shown in FIG. 1D, the sensor 100 may be in communication directlywith the auxiliary device 300. The user interface 200 thus maycommunicate with the auxiliary device 300 which may communicate with thesensor 100. Additionally, as shown in FIG. 1E, the sensor 100 maycommunicate both with the user interface 200 and with the auxiliarydevice 300.

FIGS. 1F and 1G illustrate arrangements of embodiments of the presentinvention in accordance with the data flow of FIG. 1B. As shown in FIG.1F, the sensor 100 may be tethered to the user interface 200 by a wire900, and the user interface 200 may be tethered to the auxiliary device300 by a wire 900. As shown in FIG. 1G, even if the sensor 100 istethered to the user interface 200 by a wire 900, the user interface 200may communicate wirelessly with the auxiliary device 300.

One or more of the auxiliary devices may be in communication with apersonal computer or server, so that sensor measurements are sent to thepersonal computer or server. As shown in FIG. 1H, one or more of theauxiliary devices 300 may be in communication with a personal computeror server 500, and blood glucose (BG) reference measurements from a BGmeter 700 or a laboratory measurement are sent to the personal computer.Thus, reference measurements may be sent to a personal computer orserver 500, and then sent to the user interface 200. These referencemeasurements may be used for calibration of the sensor data. As shown inFIG. 1H, the user interface 200 may communicate with the personalcomputer or server 500 through one or more other auxiliary devices 300,such as a patient monitor. The communication with the BG meter 700 andthe user interface 200 may also be through one or more of the auxiliarydevices 300. Also as shown in FIG. 1H, the user interface 200 maycommunicate through a docking station 220. The BG meter 700 may also beplaced in a docking station 720. The sensor measurements may be storedon a server and made available to one or more PCs. Thus in one example,sensor information can be downloaded to a first PC, the BG meterreference measurements can be downloaded or entered into a second PC,the first PC and the second PC can communicate with each other (such asthrough a server), the reference measurements can be sent to the userinterface, and the sensor measurements and/or reference measurements canbe viewed at any of the PCs that are connected to the shared server. Oneor more devices, such as the user interface and/or the BG meter may useone or more cradles to connect the device to a PC. Alternatively, thereference measurements are sent to a PC, the processed sensor signal issent to a PC, and the PC calculates the sensor measurements.Alternatively, the user interface may communicate with a personalcomputer using radio frequency (RF) (not shown). Examples of devices tofacilitate communication with the personal computer include, withoutlimitation, communications linking devices such as the ComLink™ sold byMedtronic MiniMed, IR cradles, RF devices, or the like that can be usedto send and/or receive signals. For example, the ComLink™ has atransceiver to receive RF signals from a user interface and thenforwards received information to the personal computer by wire.

FIGS. 2A-2S show data flow of embodiments of the present invention wherea sensor communicates with sensor electronics, which communicate to auser interface. The sensor is tethered to sensor electronics, which maycommunicate over a tethered connection or wirelessly to a user interfaceand/or auxiliary device. A more detailed discussion of the sensorelectronics is included below. As shown in FIG. 2A, a sensor 100 may bein communication with sensor electronics 120, which are in communicationwith the user interface 200.

In FIG. 2B, the user interface 200 is in communication with one or moreauxiliary devices 300, as well as in communication with the sensorelectronics 120. As shown in FIG. 2C, the user interface 200 may be incommunication with more than one auxiliary device 300. The auxiliarydevices 300 may be in communication with each other and/or incommunication with the user interface 200 and/or sensor electronics 120.

As shown in FIG. 2D, both the user interface 200 and the sensorelectronics 120 may communicate with the auxiliary device 300. And asshown in FIG. 2E, the sensor electronics 120 may be in communicationwith both the user interface 200 and the auxiliary device 300.

FIGS. 2F-2I, 2L-2O, and 2P-2S are embodiments of the present inventionin accordance with the data flow of FIGS. 2B, 2D, and 2E, respectively.They illustrate that the communications between devices may be by wire900 or may be wireless. In FIGS. 2F and 2G, the sensor 100 and sensorelectronics 120 are coupled to each other and to a connector 400. Theconnector 400 may connect the sensor electronics 120 to a wire 900 thatconnects to the user interface 200. As shown in FIG. 2F, the userinterface 200 may then be tethered to an auxiliary device 300 via a wire900. As shown in FIG. 2G, the user interface 200 may also be in wirelesscommunication with the auxiliary device 300.

In FIGS. 2H and 2I, the sensor 100 and sensor electronics 120 arecoupled to each other but communicate wirelessly to the user interface200. There need not be a connector in this embodiment, but it ispossible to have a sensor and sensor electronics that can communicatethrough wired or wireless configurations to the user interface.Therefore, the sensor and sensor electronics may be coupled to a wireconnector that is not in use when the communication is wireless. InFIGS. 2H and 2I, the sensor 100 is coupled to the sensor electronics120, which is in wireless communication with the user interface 200. Asshown in FIG. 2H, the user interface 200 may then be tethered to anauxiliary device 300 via a wire 900. As shown in FIG. 2I, the userinterface 200 may also be in wireless communication with the auxiliarydevice 300.

In FIGS. 2L and 2M, the sensor 100 and sensor electronics 120 arecoupled to each other and to a connector 400. The connector 400 mayconnect the sensor electronics 120 to a wire 900 that connects to theauxiliary device 300. As shown in FIG. 2L, the auxiliary device 300 maythen be tethered to a user interface 200 via a wire 900. As shown inFIG. 2M, the auxiliary device 300 may also be in wireless communicationwith the user interface 200.

In FIGS. 2N and 2O, the sensor 100 and sensor electronics 120 arecoupled to each other but communicate wirelessly to the auxiliary device300. In FIGS. 2N and 2O, the sensor 100 is coupled to the sensorelectronics 120, which is in wireless communication with the auxiliarydevice 300. As shown in FIG. 2N, the auxiliary device 300 may then betethered to a user interface 200 via a wire 900. As shown in FIG. 2O,the auxiliary device 300 may also be in wireless communication with theuser interface 200.

In FIGS. 2P, 2Q and 2R, the sensor 100 and sensor electronics 120 arecoupled to each other and to a connector 400. The connector 400 maycouple the sensor electronics 120 to one or more wires 900 that connectsto the auxiliary device 300 and/or the user interface 200. As shown inFIG. 2P, the sensor electronics 120 may be coupled to both auxiliarydevice 300 and user interface 200 via wires 900. As shown in FIG. 2Q,the sensor electronics 120 may be coupled to the auxiliary device 300via wire 900 and in wireless communication with the user interface 200.As shown in FIG. 2R, the sensor electronics 120 may be coupled to theuser interface 200 via wire 900 and in wireless communication with theauxiliary device 300. In FIG. 2S, the sensor 100 is coupled to thesensor electronics 120, which is in wireless communication with theauxiliary device 300 and with the user interface 200.

One or more of the auxiliary devices may be a personal computer orserver, and sensor measurements may be sent to the personal computer orserver. Additionally, blood glucose (BG) reference measurements from aBG meter or a laboratory measurement may be sent to the personalcomputer or server, and then may be sent to the user interface. As shownin FIGS. 2J and 2K, the user interface 200 may communicate with apersonal computer 500, and a BG meter 700 may communicate with thepersonal computer 500. Also as shown in FIGS. 2J and 2K, the userinterface 200 may communicate with the personal computer or server 500through one or more other auxiliary devices 300, such as a patientmonitor. The communication with the BG meter 700 and the user interface200 may also be through one or more of the auxiliary devices 300. Theuser interface 200 may communicate through a docking station 220. The BGmeter 700 may also be placed in a docking station 720. In FIG. 2J thesensor 100 is coupled to the sensor electronics 120, which is coupled toa connector 400 for coupling the sensor electronics 120 to the userinterface through a wire 900. As shown in FIG. 2K, the communicationbetween the sensor electronics 120 (coupled to the sensor 100) and theuser interface 200 may also be wireless. The sensor information may bestored on a server and made available to one or more personal computers.Thus in one example, sensor information can be downloaded to a firstpersonal computer, the BG meter reference measurements can be downloadedor entered into a second personal computer, the first personal computerand the second personal computer can communicate with each other (suchas through a server), the reference measurements can be sent to the userinterface, and the sensor measurements and/or reference measurements canbe viewed at any of the personal computers that are connected to theshared server. Alternatively, the reference measurements may be sent toa personal computer, the processed sensor signal may be sent to apersonal computer, and the personal computer may then calculate thesensor measurements.

As discussed above, the present invention may include electricalcomponents. For example, the electrical components may include one ormore power supplies, regulators, signal processors, measurementprocessors, reference memories, measurement memories, user interfaceprocessors, output devices, and input devices. The one or more powersupplies provide power to the other components. The regulator suppliesregulated voltage to one or more sensors, and at least one of the one ormore sensors generates a sensor signal indicative of the concentrationof a physiological characteristic being measured. Then the signalprocessor processes the sensor signal generating a processed sensorsignal. Then the measurement processor calibrates the processed sensorsignal using reference values from the reference memory, thus generatingsensor measurements. Then the measurement memory stores sensormeasurements. Finally, the sensor measurements are sent to the userinterface processor, which forwards the sensor measurements to an outputdevice.

The one or more power supplies may be a battery. Alternatively, the oneor more power supplies may be one or more batteries, a voltageregulator, alternating current from a wall socket, a transformer, arechargeable battery, or the like. The regulator may be a voltageregulator. Alternatively, the regulator may be a current regulator, orother regulator. The source of power for operating the sensor or forcharging a battery within sensor electronics may include an AC powersource (e.g., 110-volt or 220-volt), DC power source (e.g., a 12-volt DCbattery), or pulsating DC power source (e.g., a power charger thatprovides pulsating DC current to a battery that re-energizes the batteryand removes the lead sulfate deposits from the plates).

The signal processor may perform one or more functions such as,converting the sensor signal from an analog signal to a digital signal,clipping, summing, filtering, smoothing, and the like.

The measurement processor may perform one or more functions such as, butnot limited to, calibrating (converting the processed sensor signal intomeasurements), scaling, filtering, clipping, summing, smoothing,analyzing, and the like. The measurement processor may also analyzewhether the sensor is generating signals indicative of a physiologicalcharacteristic or whether the sensor is no longer functioning properly.For example, the measurement processor may detect that the processedsensor signal is too high, too low, changes too rapidly, or is too noisyfor a properly functioning sensor, and thus indicate that the sensorshould be replaced. The measurement processor may further analyzewhether to generate an alarm due to a characteristic of the sensormeasurement, such as the sensor measurement is too high, too low,increasing too rapidly, decreasing too rapidly, increasing too rapidlygiven its present value, decreasing too rapidly given its present value,too high for a given duration, too low for a given duration, and thelike. Additionally, the measurement processor may estimate the remainingbattery life.

The reference memory may contain one or more reference values forconverting the processed sensor signal into a sensor measurement. Forexample, 1 micro-amp (μamp) equals 40 milligrams of glucose perdeciliter of fluid (mg/dl), or 2 nano-amps equals 10 millimoles ofglucose per liter of fluid (mmol/l). Reference measurements are inputinto the input device periodically during the life of the sensor, witheach reference measurement paired with a processed sensor signal, andeach pair of a reference measurement with a processed sensor signalstored in the reference memory as a reference value. Thus, themeasurement processor may use new reference values to convert theprocessed sensor signal into sensor measurements. Alternatively, thereference values may be factory installed. Thus no periodic referencemeasurements are needed. Additionally, the reference memory may containboth factory installed reference values and periodic reference values.

The user interface processor may transfer sensor measurements from themeasurement memory to the output device. The user interface processormay also accept inputs from the input device. If the sensor includes amemory, the user interface may send parameters from the inputs to thesensor for storage in the memory. The inputs may include one or more ofcertain setup parameters, which it may be possible to change later butmay be fixed: one or more high thresholds, one or more low thresholds,one or more trend rates, alarm acknowledge, minimum time between alarms,snooze duration, sensor serial number, codes, identification numbers(ID), password, user name, patient identification, referencemeasurements, and the like. The user interface processor may also tellthe output device what to do including one or more of the following:display the latest sensor measurement, display the latest referencemeasurement, display a graph of sensor measurements, display thresholds,activate an alarm, display a message such as an alarm message, an errormessage, a command, an explanation, a recommendation, a status, and thelike. Additionally, the user interface processor may perform one or moreprocessing or analyzing functions such as, calibrating, scaling,filtering, clipping, summing, smoothing, calculating whether the sensoris generating signals indicative of a physiological characteristic orwhether the sensor is no longer functioning properly, estimatingremaining battery life, determining whether to generate an alarm due toa characteristic of the sensor measurement, and the like.

If one or more electrical components reside in the same device, then oneor more of the electrical components may be combined into a singleelectrical component, such as combining the user interface processor,measurement processor and the signal processor; or combining themeasurement memory and the reference memory. Alternatively, thecomponents may be independent despite in which device they reside.

It is possible that a sensor will need to receive regulated power for adefined duration before it can generate a stable signal, in other wordsit must warm up. And, if regulated power is removed from the sensor, thesensor must warm up again when the power is restored before measurementscan be used. Alternatively, it is possible that each time the sensor iswarmed up, new reference measurements must be input and paired with aprocessed sensor signal to create new reference values, which are storedin the reference memory. Reference values are needed to calibrate theprocessed sensor signal into sensor measurements. Furthermore, periodicreference values may be needed, and if a stable (warmed up) processedsensor signal is not available when a new reference values is needed,then a new reference measurement may have to be collected when theprocessed sensor signal is available and stable. In the mean time theprocessed sensor signal cannot be used to generate a sensor measurement.In other words, if it is time for a new reference measurement tomaintain calibration and the sensor signal is not available to pair withthe new reference measurement, then the sensor loses calibration andwill have to be recalibrated when the sensor signal becomes available.It is also possible that more than one reference value will need to becollected before the sensor measurement is considered calibrated.

There is a possibility, particularly in a hospital environment, that thesensor may be disconnected from the user interface and/or from thepatient monitor for extended periods of time. For example, patients aremoved between rooms and beds regularly when the may not be connected toany patient monitor (e.g. a surgery patient may move from admission tosurgery to recovery, and so forth). In some cases, calibration will bescheduled at particular intervals. When the sensor, coupled to sensorelectronics, is disconnected from the user interface and/or patientmonitor, one of these intervals may occur. For such a situation, it isuseful to have a way to calibrate the sensor and sensor electronicswhile separated from the user interface and/or patient monitor. Forexample, the sensor may include a blood glucose (BG) meter to supportcalibration. The BG meter may be display-free to, for example, reduceexcess size and weight. The BG meter included in the sensor would thenprovide reference values for calibration to the sensor electronics. Itis also possible to couple the sensor electronics to a BG meter or touse a wireless connection to the BG meter to receive the referencevalues.

FIGS. 3A-3C and 4A-4C illustrate physical embodiments of aspects of thepresent invention. FIGS. 3A-3C show sensors with and without sensorelectronics with connectors 400, so that they may be wired to one ormore devices. In the embodiments shown in FIGS. 1A-1H, discussed above,there is a connector 400 between the sensor 100 and a device, which isnot shown. FIG. 3A illustrates a simple sensor in accordance with theinvention as embodied in FIGS. 1A-1H. The sensor 100 includes theconnector 400. The sensor 100 is not always wired to a device. Forexample, as shown in FIGS. 3C, 4A, and 4B, the sensor 100 shown in FIG.3A may be coupled to sensor electronics. In this particular embodiment,however, the sensor 100 does not include sensor electronics.

There are a number of ways to include sensor electronics in the sensorof the present invention. As shown in FIG. 3B, the sensor 100 mayinclude a connector 400 and the sensor electronics may be a monolithicpart of the sensor. In FIG. 3B, electrical components, specifically theregulator 1090 and sensor power supply 1210, are shown directly on thesensor 100. Alternatively, the sensor electronics 120 may be coupled tothe sensor 100 by a connector 450, such as shown in FIG. 3C. The sensorelectronics 120 in FIG. 3C include one or more electrical components,such as the regulator 1090 and sensor power supply 1210 and may be wiredto one or more devices through connector 400.

FIGS. 4A-4C show sensors which are intended to be used for wirelesscommunication with one or more devices. As shown in FIG. 4A, the sensor100 may be coupled to the sensor electronics 120 by a connector 450. Thesensor electronics 120 may include one or more electrical components,such as the regulator 1090 and sensor power supply 1210. As shown inFIG. 4B, the sensor may be coupled to a sensor electronics 120 thatinclude a portion coupled to the sensor via a connector 450 and wired toa separate portion 140, which includes sensor electronics. Although thesensor electronics are shown as having electrical components on only oneportion, it is possible to have some electrical components on oneportion of the sensor electronics and other electrical components onanother portion. Embodiments shown in FIG. 4B are discussed in moredetail in U.S. patent application Ser. No. 09/465,715, filed Dec. 17,1999, which is herein incorporated by reference. As shown in FIG. 4C,the sensor electronics may be a monolithic part of the sensor 100.

Many different wireless communication protocols may be used. Someprotocols are for one-way communication and others are for two-waycommunication. For one-way communication, the transmitting device mayhave a transmitter and the receiving device may have a receiver. Fortwo-way protocols, each device typically has a transceiver, but eachdevice could have a transceiver and a receiver. For any wirelessembodiment, a transceiver may be used in place of a receiver or atransmitter, because the transceiver can perform like a receiver or atransmitter or both.

Where the sensor electronics 120 (wired or wireless) are separated fromthe sensor 100 by a connector 450, such as shown in FIGS. 3C, 4A, and4B, the sensor electronics may first become powered by the sensor powersupply at the time that the sensor electronics are attached to thesensor. Thus, the sensor power supply shelf life is increased.Alternatively, the sensor electronics may always be powered. The sensorelectronics may be powered by the sensor power supply when triggered byother means, such as when the user interface is connected to the sensorelectronics, when a magnetic switch is triggered, when a mechanicalswitch is triggered, or the like.

The duty cycle of the sensor power supply may vary based on the sensorelectronics being connected or disconnected from the user interfaceand/or patient monitor. For example, when the sensor electronics aredisconnected, the duty cycle may be reduced (e.g., by using fewerelectrical components, by decreasing data acquisition, and the like),which will allow for a greater sensor power supply shelf life. If thesensor and sensor electronics lose power for a prolonged period of time,the calibration process may have to be repeated. The sensor electronicsmay include circuitry to detect low battery levels and may be coupled toan alarm that will activate if the low battery level reaches a certainthreshold.

FIGS. 5A-5H are block diagrams of the electronic components ofembodiments of aspects of the present invention. In the embodiment shownin FIG. 5A, the user interface 200 is tethered to the sensor 100. Thetether may be interrupted by a connector 400 so that the sensor 100 andthe user interface 200 can be separated. The sensor 100 does not includea power supply in FIG. 5A. When the patient disconnects a sensor fromthe user interface 200, then the sensor no longer receives power fromthe regulator and thus may require time to warm up again and may requirere-calibration when re-connected with the user interface.

The user interface power supply 1030 supplies power to the userinterface 200 and may also supply power to the sensor 100. The regulator1090 supplies regulated voltage to sensor 100, and the sensor 100generates a sensor signal indicative of the concentration of aphysiological characteristic being measured. Then the signal processor1080 processes the sensor signal generating a processed sensor signal.Then the measurement processor 1070 calibrates the processed sensorsignal using reference values from the reference memory 1050, thusgenerating sensor measurements. Then the measurement memory 1060 storessensor measurements. Finally, the sensor measurements are sent to theuser interface processor 1040, which forwards the sensor measurements toan output device 1010. The reference values, and other useful data, maybe input through an input device 1020.

As shown in FIG. 5B, an auxiliary device 300 may be tethered to thesensor 100, and the tether may be interrupted by a connector 400 so thatthe sensor 100 and the user interface 200 can be separated. Thus, apatient wearing a sensor does not have to remain tethered to a device,such as a user interface or an auxiliary device. The user can wear thesensor and temporarily or permanently disconnect from other devices.This can be useful if the patient needs to leave the proximity of one ormore devices. For example, the sensor may be tethered to a stationarydevice such as a wall-mounted or bed-mounted display, and the patientmust leave the room for a therapeutic procedure. As shown in FIG. 5B,the auxiliary device may include an auxiliary device power supply 1110,regulator 1090 and the signal processor 1080, so that the auxiliarydevice processes the sensor signal.

In the above embodiments, where the sensor does not include a powersupply, when the sensor is disconnected from the other devices, thesensor no longer receives power. The tether includes one or more wiresto carry the regulated voltage to the sensor and carry the sensor signalto the signal processor. For particular types of sensors, the sensormust be warmed up again when re-connected with the user interface. Wherethe reference memory is included in the user interface, one or morereference values may be periodically measured and stored in thereference memory when they are collected. If the sensor is disconnectedfrom the user interface when a new reference value is required, however,the sensor will need calibration when it is re-connected.

One or more devices other than the sensor may be in communication witheach other, such as discussed above in reference to FIGS. 1B-1H. The oneor more devices other than the sensor, such as an auxiliary device and auser interface, may share a tethered connection such as a wire. As usedherein the term “wire” means and includes any physical conductor capableof transmitting information by non-wireless means including, forexample, one or more conventional wires, a serial or parallel cable, afiber optic cable, and the like. The term “wire” also includes anyphysical conductor capable of carrying regulated voltage, electricalpower, and the like. Additionally, the tethered connections may includeat least one connector so that at least one device can be separated fromthe others. One or more of the one or more devices other than thesensor, such as an auxiliary device and a user interface, maycommunicate wirelessly, such as RF, IR, sub-sonic, and the likecommunications, such as shown in FIG. 1G.

Alternatively, the user interface may be coupled to sensor electronics,which may be coupled to the sensor, such as shown in FIGS. 5C-5H. If apower supply and regulator stay with the sensor (as part of the sensorelectronics), when the sensor is disconnected from the user interface,then the sensor can remain powered and retain calibration. Thus, thesensor may not require warm up time and may not require re-calibrationwhen re-connected to the same user interface that it was connected topreviously.

The sensor power supply may be a battery capable of operating for atleast the entire life of the sensor. For example, the life of the sensormay be, for example, about 2 days, 3 days, 4 days, 5 days, 7 days, 10days, 20 days, 30 days, 45 days, 60 days, a year, and the like.Alternatively, the life of the sensor may be shorter than 2 days, suchas, about 36 hours, 30 hours, 24 hours, 12 hours, 6 hours, 3 hours andthe like. The sensor power supply may be rechargeable. For example, thesensor power supply may be recharged when the sensor electronics areconnected to the user interface. Additionally, the sensor power supplymay be sized to last the entire duration that the sensor electronics aredisconnected from the user interface, such as 15 minutes, 30 minutes, 1hour, 2 hours, 3 hours, 4 hours, 6 hours, 8 hours, 12 hours, 24 hours,and the like. The sensor power supply may include one or more of atransformer, capacitor, power cell, solar cell, replaceable battery, andthe like. Alternatively, the sensor power supply is a replaceablebattery.

In the embodiment shown in FIG. 5C, the sensor electronics 120 include asensor power supply 1210 and regulator 1090. Thus, when the sensor 100is disconnected from the user interface 200, the sensor 100 remainspowered. Because the sensor electronics do not include memory storage,the sensor data is not saved while the sensor 100 is not connected tothe user interface 200.

As shown in FIG. 5E, it is possible to transport reference values withthe sensor 100 so that the reference values are kept with the sensor 100even when the sensor 100 is no longer connected to the user interface200. In this embodiment, a sensor power supply 1210 and regulator 1090and reference memory 1050 are included in the sensor electronics 120that stay with the sensor 100 when disconnected from the user interface200 at connector 400. When the sensor 100 is disconnected from the userinterface 200, the sensor 100 may remain powered and retain calibration.Thus, the sensor 100 does not require re-calibration when re-connected.Furthermore, the sensor 100 may be connected to a different userinterface and remain calibrated, because the calibration values arecarried along with the sensor 100 and can be sent to the different userinterface. If BG meter readings are needed for calibration, they areentered into the user interface 200 and sent to the reference memory1050 in the sensor electronics 120. If BG meter readings are not needed,then the reference memory 1050 may contain factory installed referencevalues for the sensor. In the particular embodiment shown in FIG. 5E,sensor data is not collected while the sensor 100 is not connected to auser interface.

As shown in FIGS. 5D and 5F, the sensor electronics 120 may include asignal processor 1080. The signal processor simplifies communicationacross the tethered connection because the signal processor can convertweak analog sensor signals (which might be especially sensitive tonoise) into digital signals, which can be made highly resistant tonoise. Often, wires behave like antennas and gather radio frequencysignals and the like, thus adding noise to signals carried on the wires.

As shown in FIGS. 5E-5H, the user interface 200 may be tethered to thesensor electronics 120, and the sensor electronics 120 may include areference memory 1050. One or more reference values may be periodicallymeasured, entered into the user interface 200 and transferred to thereference memory 1050, as shown in FIGS. 5E and 5G. If the sensor 100 isdisconnected from the user interface 200 when a new reference value isrequired, the sensor 100 will need calibration when it is re-connected.As shown in FIGS. 5E and 5G, the power supply 1210, regulator 1090 andreference memory 1050 may be included with the sensor electronics 120.If the sensor 100 is disconnected from the user interface 200, thesensor 100 remains powered and retains calibration. Thus, the sensordoes not require re-calibration or warm up when re-connected.Furthermore, the sensor may be disconnected from a first user interfaceand then connected to a second user interface and remain calibratedbecause the calibration values are carried along with the sensor and canbe sent to the second user interface.

As shown in FIGS. 5E, and 5F, the sensor electronics 120 includes thereference memory 1050, sensor power supply 1210 and regulator 1090, butdoes not include the measurement memory 1060. Since the measurementmemory 1060 is not included with the sensor electronics 120, the sensordata is not collected while the sensor 100 is not connected to a userinterface. Furthermore, if periodic reference measurements are required,and the sensor electronics 120 are disconnected from the user interface200 at the time that a new reference measurement is needed, then thesensor 100 will lose calibration, and a new reference measurement willbe needed when the sensor electronics 120 are reconnected to a userinterface.

As shown in FIG. 5G, the sensor electronics 120 may include thereference memory 1050, sensor power supply 1210, regulator 1090, signalprocessor 1080, measurement processor 1070, and the measurement memory1060. Since the measurement memory 1060 is included with the sensorelectronics 120, the sensor data is collected even while the sensor 100is not connected to a user interface. Thus, a patient wearing a sensormay move about freely while disconnected from the user interface, andwhen they reconnect, all of the sensor data can be sent to the userinterface for analysis and display. If however, periodic referencemeasurements are required, and the sensor electronics are disconnectedfrom the user interface at the time that a new reference measurement isneeded, then the sensor may lose calibration, and a new referencemeasurement will be needed when the sensor electronics are reconnectedto a user interface.

Periodic reference values may not be required. One or more referencevalues may be stored in the reference memory at the factory.Furthermore, the reference memory may be non-volatile such as a flashmemory, and therefore not require power to maintain the reference valuesas shown in FIG. 5H. Thus, reference values might be factory installedwith each sensor and no power is required to maintain the referencevalues in the reference memory. As shown in FIGS. 5E, 5F, 5G and 5H, thereference memory 1050 may be included in the sensor electronics 120.Thus, a sensor may be disconnected from a user interface and connectedto a second and not require calibration. The sensor may, however,require a warm up period if it loses power when disconnected from a userinterface as shown in FIG. 5H.

Alternatively, one or more factory installed reference values may bestored in volatile memory with each sensor, and power is required tomaintain the reference values in memory as shown in FIGS. 5E, 5F and 5G.The reference memory and a sensor power supply may optionally beincluded in the sensor electronics. Thus, a sensor may be disconnectedfrom a user interface and connected to a second and not requirecalibration and the sensor may not require a warm up period if it doesnot lose power when disconnected from a user interface.

The tether may include one or more wires or one or more fiber opticcables or the like. Alternatively, the tether may not include a wire orcable or the like if the sensor electronics includes a sensor powersupply and a regulator, and thus a wire is not needed to carry power tothe sensor.

As shown in FIGS. 6A-6E, and as discussed above with respect to FIGS.2A-2S and 4A-4C, the sensor electronics 120 may include a mechanism forwireless communication 1205, such as a radio frequency (RF) transmitteror transceiver, or an infrared (IR) transmitter or transceiver, lightemitting diode (LED), sonic transmitter such as a speaker, and the like.Sensor electronics that include wireless communication capability are asubset of all sensor electronics and are referred to as wireless sensorelectronics. Thus, a sensor may be physically coupled to wireless sensorelectronics and establish a wired connection between the wireless sensorelectronics and the sensor, but the wireless sensor electronics andsensor are not tethered to a user interface or an auxiliary device.Thus, a user can wear the sensor and move about freely, physicallydisconnect from other devices. This can be useful if the patient needsto leave the proximity of one or more devices. For example, if thepatient is wearing a sensor with wireless sensor electronics thatcommunicate with a stationary device such as a wall-mounted orbed-mounted display, then the patient may leave the room for atherapeutic procedure without having to disconnect the sensorelectronics from any devices. Communication between the sensorelectronics and one or more devices may be interrupted and may bere-established later. For example, the sensor electronics may betemporarily moved out of range for RF communication with a wall mounteddevice, or may be temporarily misaligned for IR communication with oneor more devices.

The sensor wireless communication mechanism may be a processor thathandles the communication protocol and manages transferring informationin and out of the reference memory and the measurement memory. Themeasurement memory may contain one or more of calibrated measurements,time and dates associated with measurements, raw un-calibratedmeasurements, diagnostic information, alarm history, error history,settings and the like. Settings may be determined by a user using akeypad on the user interface, and the settings are sent to a memory inthe sensor electronics. Additionally, the sensor wireless communicationmechanism may be a processor that evaluates the calibrated measurementsaccording to user defined settings and sends results of the evaluationto the user interface. For example, the user may set an alarm threshold,which is sent to be stored in a memory in the sensor electronics. Thenthe sensor wireless communication mechanism compares a calibratedmeasurement to the alarm threshold and if the calibrated measurementexceeds the alarm threshold, the communication system sends an alarmmessage to the user interface. Finally, the user interface displays thealarm message.

The alarms may function even when the sensor and sensor electronics aredisconnected from the user interface and/or patient monitor. In thisway, the patient will be warned if he/she becomes hyperglycemic orhypoglycemic, even when not connected to the user interface and/orpatient monitor. For example, the sensor electronics may be coupled toan alarm. As discussed above, an alarm threshold may be stored in amemory in the sensor electronics. If a calibrated measurement exceedsthe alarm threshold, the alarm coupled to the sensor electronics may beactivated. Similarly, if a battery is low on power, or the sensor is notperforming properly, or communication with another device has been lost,or an error has occurred, or a warning is needed, then the sensorelectronics may activate an alarm. The alarm may be an audible alarm, avisible alarm, a tactile alarm (such as a vibrating alarm), or anycombination thereof. In particular embodiments, the sensor electronicsincludes one or more components for alarming a user.

User defined parameters such as alarm thresholds, minimum time betweenalarms, alarm snooze time, trend alarm thresholds, patient ID, one ormore identifying codes, a password, and the like may be sent from theuser interface to the sensor electronics and stored in memory in thesensor electronics. Thus, settings that are established for a particularpatient are not lost when the patient is moved to a new location and thesensor electronics establishes communication with a second userinterface. The user defined settings are sent to the second userinterface when communication is first established with sensorelectronics. Each set of sensor electronics may have a unique ID, code,name, serial number, or the like, which is sent to the user interface sothat the user interface can identify which sensor electronics it iscommunicating with. The unique ID for a sensor electronics may berequired to be entered into a user interface before the user interfacewill recognize communications from a sensor electronics. Thus, if a userinterface detects communication from more than one sensor electronics,then user interface can determine which signal to respond to based onthe unique ID contained in the communications. Furthermore, the userinterface and/or auxiliary devices may have one or more unique IDs sothat each device, user interface, and sensor electronics can determinewhether to accept communications from each other. For example, a patientmonitor may be programmed to accept communications from a user interfaceor sensor electronics as long as the communication includes a unique IDrepresenting a particular sensor. Thus, if two patients share a room andtransmissions from a first patient's sensor electronics are received bya second patient's user interface and/or patient monitor, the secondpatient's user interface and/or patient monitor will ignore thecommunication. Yet, the first patient's user interface and/or patientmonitor will accept the communication from the first patient's sensorelectronics. In another example, a user interface ID number is enteredinto a patient monitor, and the patient monitor will only acceptcommunications that contain the user interface ID number.

FIGS. 6A-6E show similar embodiments to FIGS. 5A-5H. However, as shownin FIGS. 6A-6C, the sensor electronics 120 include sensor wirelesscommunication mechanism 1205 and the user interface 200 includes userinterface wireless communication mechanism 1005. As shown in FIG. 6A,the sensor power supply 1210 and regulator 1090 are part of the sensorelectronics 120. Thus, the sensor 100 constantly remains powered. Asshown in FIG. 6B, the signal processor 1080 may reside in the sensorelectronics 120, so that the sensor 100 can remain powered but can alsoperform processing. In particular embodiments, if the signal processor1080 includes an analog to digital converter. Thus, digitalcommunication can be used to send the processed sensor signal to theuser interface 200.

Once the sensor is powered and warmed up by the sensor power supply andthe regulator, the sensor remains powered and sufficiently warmed up andthus does not need to warm up again no matter how many different devicesit communicates with. One or more reference values may be measuredperiodically and stored in the reference memory when they are collected.If the wireless sensor electronics cannot establish communication withuser interface when a new reference value is required, the sensor willneed calibration when communication is re-established.

As shown in FIG. 6C, the sensor power supply 1210, regulator 1090 andreference memory 1050 may stay with the sensor 100. Then if the sensor100 loses communication with the user interface 200 (such as because thepatient walks too far away from the user interface), then the sensorremains powered and retains calibration. Thus, the sensor 100 does notrequire re-calibration or warm up time when it re-establishescommunication with the user interface 200. Furthermore, the sensor 100may establish communication with a second user interface and remaincalibrated because the calibration values are carried along with thesensor 100 and can be sent to the second user interface. As shown inFIG. 6D, the wireless sensor electronics may include the referencememory 1050, sensor power supply 1205, regulator 1090, signal processor1080 and a wireless communication mechanism 1205, but does not includethe measurement memory 1060. Since the measurement memory is notincluded with the wireless sensor electronics, the sensor data is notcollected while the wireless sensor electronics is not in communicationwith a user interface. Furthermore, if periodic reference measurementsare required, and communication cannot be established between thewireless sensor electronics and the user interface at the time that anew reference measurement is needed, then the sensor will losecalibration, and a new reference measurement will be needed when thewireless sensor electronics and a user interface have establishedcommunication.

As shown in FIG. 6E, in addition to the sensor power supply 1210,regulator 1090, reference memory 1050, the measurement memory 1070 andmeasurement processor 1060 may stay with the sensor 100. Whencommunication is lost between the sensor electronics 120 and the userinterface 200, the sensor 100 remains powered, retains calibration andcollects and stores measurements. Thus, the sensor 100 does not requirere-calibration or warm up when communication is established with anyuser interface. A patient wearing a sensor may move about freely, andwhen the wireless sensor electronics establishes communication with auser interface all of the sensor data can be sent to the user interfacefor analysis and display. If however, periodic reference measurementsare required, and the wireless sensor electronics and user interfacecannot establish communication at the time that a new referencemeasurement is needed, then the sensor may lose calibration, and a newreference measurement will be needed when the wireless sensorelectronics are in communication with a user interface.

Alternatively, periodic reference values are not required. One or morereference values may be stored in the reference memory at the factory.Furthermore, the reference memory may be non-volatile such as a flashmemory, and therefore not require power to maintain the referencevalues. Thus, reference values might be factory installed with eachsensor and no power would be required to maintain the reference valuesin the reference memory. The reference memory may be included in thewireless sensor electronics. Thus, calibration would not be requiredwhen the sensor electronics establishes communication with a userinterface.

Alternatively, one or more factory installed reference values may bestored on a volatile reference memory in wireless sensor electronicsthat are included with each sensor. In this case, power could be neededto maintain the reference values in memory. Alternatively, the referencememory and a sensor power supply are included in the wireless sensorelectronics.

If the reference values are factory installed, they may be included on aCD, floppy disk, or other removable storage devices. If the referencevalues are stored on a CD, for example, they may be downloaded into apersonal computer and then downloaded into the user interface and/orsensor electronics. The reference values may also be stored on aremovable or non-removable non-volatile memory. For example, if thereference values are stored on a removable non-volatile memory, thememory may be included in a flash memory card. The flash memory card maybe adapted to be used in the user interface and/or the sensorelectronics. The reference values may be stored on a non-volatile orvolatile memory that is included with the sensor electronics at thefactory. In this case, if the memory included with the sensorelectronics is volatile, the sensor electronics should include a powersource so that the sensor electronics may retain the reference valuesduring shipping and storage. One set of sensor electronics may containreference values to calibrate a number of sensors. For example, if asensor electronics is shipped with a number of sensors, the referencevalues may calibrate all of those sensors.

As shown in FIG. 7, the user interface 200 and/or the sensor electronics120 may include a slot 260, 160 for a flash memory card 600. The flashmemory card 600 may include reference values that are factory input orreference values that are input later. Additionally, the flash memorycard 600 may store additional desired data. The flash memory card 600may be included when the user interface 200 and/or sensor electronics120 is shipped from a factory or reseller. Or, the flash memory card 600may be purchased separately for use with the user interface 200 and/orthe sensor electronics 120. Additionally, a flash memory card may beused in the patient monitor.

As noted above with respect to FIGS. 6C, 6D, and 6E, the wireless sensorelectronics 120 may include a reference memory 1050. One or morereference values may be periodically measured, entered into the userinterface and sent to the reference memory 1050. If communication cannotbe established between the wireless sensor electronics 120 and the userinterface 210 when a new reference value is required, the sensor 100will need calibration when it is re-connected. Alternatively, referencemeasurements are sent directly to the wireless sensor electronics 120.Some examples include: a BG meter with an IR transmitter sends areference measurement to the wirelesses sensor electronics which includean IR receiver; a BG meter with RF communication capability sends a BGvalue to a wireless sensor electronics with an RF receiver; and alaboratory analyte measurement machine analyzes a blood sample and theresult of the analysis is sent to an RF transmitter which transmits theresult to the wireless sensor electronics.

Alternatively to the types of memory discussed above, a removablenonvolatile reference memory may be filled at the factory with referencevalues for calibrating one or more sensors. The removable nonvolatilereference memory may be a flash media such as a flash card, memorystick, and the like. The reference memory may be placed into the userinterface and/or into the sensor electronics. The removable nonvolatilereference memory may be placed into a device such as, an auxiliarydevice, a meter, a BG meter, a palm pilot, a phone, a PDA, a handhelddevice, a patient monitor, a module that connects to a device, and thelike. If a new sensor cannot be calibrated with a removable nonvolatilereference memory that is presently in a device, then the sensor will beaccompanied with a new removable nonvolatile reference memory for use ina device.

An auxiliary device may provide power to a user interface, which in turnpowers the sensor. The user interface may have a rechargeable powersource that provides power to the user interface whenever power is notsupplied by the auxiliary device. For example, an auxiliary device suchas a patient monitor may provide power along a wire through a connectorto a user interface; the user interface has a power supply; a sensor isconnected by a wire to the user interface; the power from the auxiliarydevice powers a voltage regulator in the user interface, which powersthe sensor. If the user interface is disconnected from the auxiliarydevice, the user interface power supply continues to supply power to thesensor. Alternatively, the auxiliary device may charge the userinterface power supply whenever the auxiliary device is connected to theuser interface, and the user interface may power the sensor whether ornot the auxiliary device is connected to the user interface.

The sensor may be powered by sensor electronics, which are powered by adevice such as an auxiliary device or a user interface. The sensorelectronics may have a rechargeable power supply that keeps the sensorpowered whenever power is not supplied by a device.

The power needed to operate a sensor may be generated at a device suchas a user interface or an auxiliary device, carried over one or morewires, passed through a transformer and supplied to the sensor.Alternatively, the power may be passed through a regulator such as avoltage regulator and a current regulator before it is supplied to asensor. The transformer may be located in the device or the transformermay be part of the wire or cable connecting the sensor to the device.The transformer also may be in the sensor electronics. The transformerkeeps the sensor powered as long as the sensor is connected to thedevice. The transformer helps to remove a ground connection between thedevice and the sensor, and therefore isolates the patient from theground voltage in the device.

The sensor signal may be passed to one or more devices before it isprocessed. For example, the sensor signal could be carried along a wireto a user interface, and then carried along a wire to an auxiliarydevice before it is processed. In another example, the sensor signal iscarried to a computer, sent through a server or a router to a secondcomputer, and then processed.

The user interface may process the sensor measurements to generateinsulin delivery commands. The insulin delivery commands may be infusionrates. Alternatively, the insulin delivery commands may be insulinamounts.

An auxiliary device may process the sensor measurements to generateinsulin delivery commands. Alternatively, sensor electronics may processthe sensor measurements to generate insulin delivery commands.

The insulin delivery commands may be generated in the device thatcontains the measurement processor. Alternatively, the insulin deliverycommands may be generated by a device that receives sensor measurements,such as an auxiliary device, a pump, and the like. Still alternatively,the insulin delivery commands are generated by an insulin infusion pumpsuch as shown in U.S. Pat. Nos. 4,562,751, 4,678,408, 4,685,903,5,080,653, 5,097,122, and 6,554,798, which are herein incorporated byreference.

While the description above refers to particular embodiments of thepresent invention, it will be understood that many modifications may bemade without departing from the spirit thereof. The accompanying claimsare intended to cover such modifications as would fall within the truescope and spirit of the present invention.

The presently disclosed embodiments are therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims, rather than theforegoing description, and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

1. A system for sensing blood glucose concentration of a person, thesystem comprising: a sensor to sense blood glucose data; sensorelectronics attached to the sensor and configured to communicate withthe sensor, the sensor electronics including a sensor power supply tosupply power to the sensor, said sensor power supply being activatedwhen the sensor is connected to a device selected from the groupconsisting of a user interface and a patient monitor; a user interfaceconfigured to communicate wirelessly with the sensor electronics; and apatient monitor configured to communicate wirelessly with the userinterface and including a display to display information representativeof the blood glucose data sensed by the sensor, wherein the sensor powersupply continues to supply power to the sensor when the sensorelectronics are not in communication with the user interface and thepatient monitor.
 2. The system of claim 1, wherein the sensorelectronics include memory to store information representative of theblood glucose data sensed by the sensor and to store reference valuesfor calibration of the blood glucose data received from the sensor. 3.The system of claim 2, wherein the user interface includes an input forinputting information into the memory of the sensor electronics.
 4. Thesystem of claim 1, wherein the sensor power supply comprises at leastone battery.
 5. The system of claim 4, wherein the at least one batteryis rechargeable, and at least one of the user interface and the patientmonitor includes a power source for providing power to the sensorelectronics for recharging the at least one battery.
 6. The system ofclaim 1, wherein the sensor electronics include a processor to processthe blood glucose data received from the sensor.
 7. The system of claim1, wherein the sensor includes a connector, and the sensor electronicsare attached to the sensor using the connector.
 8. The system of claim1, wherein the sensor electronics are configured to communicate with asecond user interface separate from said user interface and said patientmonitor.
 9. The system of claim 1, wherein the sensor is a real-timesensor to sense blood glucose data in real time.
 10. A system forsensing blood glucose concentration of a person, the system comprising:a sensor to sense blood glucose data; sensor electronics attached to thesensor and configured to communicate with the sensor, sensor electronicsincluding a sensor power supply to supply power to the sensor, saidsensor power supply being activated when the sensor is connected to adevice selected from the group consisting of a user interface and apatient monitor; and a user interface configured to communicatewirelessly with the sensor electronics, wherein the sensor power supplycontinues to supply power to the sensor when the sensor electronics arenot in communication with said device.
 11. The system of claim 10,wherein the sensor electronics include memory to store informationrepresentative of the blood glucose data sensed by the sensor and tostore reference values for calibration of the blood glucose datareceived from the sensor.
 12. The system of claim 11, wherein the userinterface includes an input for inputting information into the memory ofthe sensor electronics.
 13. The system of claim 10, wherein the sensorpower supply comprises at least one battery.
 14. The system of claim 13,wherein the at least one battery is rechargeable, and said deviceincludes a power source for providing power to the sensor electronicsfor recharging the at least one battery.
 15. The system of claim 10,wherein the sensor electronics include a processor to process the bloodglucose data received from the sensor.
 16. The system of claim 10,wherein the sensor includes a connector, and the sensor electronics areattached to the sensor using the connector.
 17. The system of claim 10,wherein the sensor electronics are configured to communicate with asecond user interface separate from said device.
 18. The system of claim10, wherein the sensor is a real-time sensor to sense blood glucose datain real time.